From: "Christian D. Odhner" <cdodhner@indirect.com>
Date: Tue, 3 May 94 01:13:51 PDT
To: Black Unicorn <unicorn@access.digex.net>
Subject: Re: Digital Cash
In-Reply-To: <199405030650.AA25513@access3.digex.net>
Message-ID: <Pine.3.89.9405030107.A13623-0100000@id1.indirect.com>
MIME-Version: 1.0
Content-Type: text/plain


In _Applied Cryptography_ by Bruce Schneier, he refers to a system 
proposed by Tatsuaki Okamoto and Kazuo Ohta that meets the following 
criteria:
	Independance. The security of the digital cash is not dependant 
on any physical location. The cash can be transfered through a computer 
network.
	Security. The digital cash cannot be coppied and reused.
	Privacy (untraceability). The privacy of the users is protected; 
no one can trace the relationship between users and their purchases.
	Off-Line Payment. When a user pays for a purchase with electronic 
cash, the protocall between the user and the merchant is executed off-line.
	Transferability. The digital cash can be transfered to other users.
	Divisability. A piece of digital cash in a given amount can be 
subdivided into pieces of cash in smaller amounts.

The reference given for this paper is as follows:

T. Okamoto and K. Ohta,"Universal Electronic Cash,"
Advances in Cryptology--CRYPTO '91 Proceedings,
Berlin: Springer-Verlag, 1992, pp. 324-337

Happy Hunting, -Chris.

______________________________________________________________________________
Christian Douglas Odhner     | "The NSA can have my secret key when they pry
cdodhner@indirect.com	     | it from my cold, dead, hands... But they shall
pgp 2.3 public key by finger | NEVER have the password it's encrypted with!"
cypherpunks         WOw            dCD           Traskcom          Team Stupid
  Key fingerprint =  58 62 A2 84 FD 4F 56 38  82 69 6F 08 E4 F1 79 11 
------------------------------------------------------------------------------

On Tue, 3 May 1994, Black Unicorn wrote:

> 
> So has anyone tried to solve the problem of double spending and
> the online requirement of digital cash?
> 
> It seems digitial cash is really only digital "check" right now as
> it must be verified at the bank before it can be show to be "valid."
> 
> Is there any way to take cash offline?  Or is this merely the copy
> protection problem rehashed?
> 
> -uni- (Dark)
>